Nanostructured sensors are widely used in the medical and chemical industries to measure the presence and/or concentration of a desired compound in a sample such as an analyte or other molecules. Nanostructured sensors typically require only a very small sample and are typically very sensitive. Common nanostructured sensors use electrical based detection such as, for example, field-effect transistors (FET). Typically, these sensors include semiconducting material located between two electrodes, whereby the semiconducting material is functionalized with a binding agent such as an antibody or aptamer. Binding a compound of interest or target molecule to the binding agent on the surface of the sensor induces electrical property changes through the semiconducting material and, thus, can be measured and correlated to the concentration of the compound within the sample. When seeking the concentration of a biological sample or biomolecule such as, for example, in medical and clinical analyzers, these nanostructured sensors are often referred to as biosensors. Biosensors are commonly used to measure the concentration of an analyte such as an antibody, an antigen, etc. in a sample fluid such as serum, blood, or urine.
Salt or ions build up at the biosensors and reduce sensitivity. Some example methods of desalting or deionizing samples utilize offline treatments with an ultrafiltration membrane. These methods suffer in that analytes that are present in low concentration may be lost during the filtration steps. Other example methods utilize desalting solutions such as dialysis, gel filtration columns, and on-chip membranes. These methods also suffer from drawbacks including potential loss of low-abundance proteins, increased cost, and increased complexity.